Titanium Nitride Thin Film Based Low-Redox-Interference Potentiometric pH Sensing Electrodes.

In this work, a solid-state potentiometric pH sensor is designed by incorporating a thin film of Radio Frequency Magnetron Sputtered (RFMS) Titanium Nitride (TiN) working electrode and a commercial Ag|AgCl|KCl double junction reference electrode. The sensor shows a linear pH slope of -59.1 mV/pH, R ² = 0.9997, a hysteresis as low as 1.2 mV, and drift below 3.9 mV/hr. In addition, the redox interference performance of TiN electrodes is compared with that of Iridium Oxide (IrO ₂ ) counterparts. Experimental results show -32mV potential shift (E ⁰ value) in 1 mM ascorbic acid (reducing agent) for TiN electrodes, and this is significantly lower than the -114 mV potential shift of IrO ₂ electrodes with sub-Nernstian sensitivity. These results are most encouraging and pave the way towards the development of miniaturized, cost-effective, and robust pH sensors for difficult matrices, such as wine and fresh orange juice.